The present invention relates to a machine tool system and a machining liquid supply device thereof. More particularly, the present invention relates to a machine tool system and a machining liquid supply device thereof capable of most properly achieving the removal of chips and the cooling of a workpiece with a machining liquid by always spouting it from an optimal position, and in an optimal direction, relative to a part of the workpiece being machined during the machining of the workpiece with a tool. The present invention also relates to a machine tool system and a machining liquid supply device capable of spouting a machining liquid in an optimal machining liquid supply mode on a part of a workpiece being machined in accordance with the diameter and machining condition of a tool having peripheral working elements, such as a grinding wheel or various milling cutters, and in accordance with the variation of the positional relation between the tool and the workpiece when machining the workpiece with the tool.
Especially in the case where a metal workpiece is machined by a tool of a machine tool system, it is essential to supply a machining liquid over the part of the workpiece being machined in order to ensure a satisfactory cooling action for removing the heat generated in the part of the workpiece being machined and to promote the smooth machining action of the tool by removing the chips generated by the machining.
A conventional machining liquid supply device used in a conventional machine tool can be, for example, a grinding liquid supply device disclosed in Japanese Unexamined Utility Model Publication (Kokai) No. 61-124366, which is hereinafter referred to as a first prior art. This publication discloses what may be called a manually operated type of machining liquid supply device, in which a machining liquid nozzle disposed in alignment with a tangent to a grinding wheel at a grinding point is supported on a wheel guard so as to be movable in directions perpendicular to the same tangent to the grinding wheel, so that the machining liquid can be spouted in a direction tangential to the grinding wheel at the grinding point by the operator operating an adjust handle regardless of a change in the diameter of the grinding wheel. The machining liquid supply device according to the first prior art, however, is not perfectly satisfactory because, when the grinding point is changed during a process of grinding a workpiece with a grinding wheel, the machining liquid cannot be spouted in a direction tangential to the grinding wheel at a changed grinding point.
A second prior art is a method of controlling a position of a grinding liquid spouting nozzle which is disclosed in Japanese Unexamined Patent Publication (Kokai) No. 1-146662. More specifically, this patent publication discloses a method in which a grinding liquid spouting nozzle is disposed in such a manner as to be capable of being turned for indexing about a spindle holding a grinding wheel during a contour grinding process with the grinding wheel, and the grinding liquid spouting nozzle is controlled in position to direct it toward a grinding point according to a program for controlling the movement of the grinding wheel during the grinding process. In this conventional method of spouting the grinding liquid according to the second prior art, however, the spouting direction of the grinding liquid is adjusted by turning the grinding liquid spouting nozzle about the spindle when the grinding point where the grinding wheel grinds a workpiece is displaced, and therefore the grinding liquid spouting nozzle is not allowed to move radially with respect to the center of the grinding wheel. Thus, the second prior art teaches nothing about a method of correctly adjusting the grinding liquid spouting direction of the grinding liquid spouting nozzle when the grinding process is performed with a grinding wheel of a different diameter held on the spindle.
A third prior art is a water spouting device for a machining center disclosed in Japanese Unexamined Patent Publication (Kokai) No. 6-31582. This water spouting device for a machining center is capable of versatilely spouting water either in a horizontal direction or vertical direction through a water spouting nozzle to a machining point where the tool of the machining center cuts a workpiece to allow water to be spouted always toward the machining point. This water spouting device is configured such that the water spouting nozzle can be moved about a spindle holding a tool by rotation of a gearing, and when the machining point moves horizontally, the water spouting nozzle can move following the moving angle to spout water toward the machining point. When the machining point changes in height, on the other hand, the base portion of the water spouting nozzle is rotated to move the tip thereof vertically, thereby allowing the water spouting nozzle to spout water toward the machining point.
The water spouting device for a machining center according to the third prior art, however, is not configured to be movable radially with respect to the center of the tool held on the spindle. Therefore, when the diameter.of the tool changes, the water spouting direction of the water spouting nozzle, disadvantageously, cannot be adjusted with respect to the machining point with sufficient accuracy.
A fourth prior art is a grinding machine provided with a wheel guard for a grinding wheel, disclosed in U.S. Pat. No. 4,619,078. In this known grinding machine, this wheel guard covers the grinding wheel held on a spindle and carries a machining liquid supply nozzle, which is configured to be turnable about the spindle together with the wheel guard and to be movable radially with respect to the spindle in accordance with the diameter of the grinding wheel, thereby supplying the machining liquid to the contact point between the grinding wheel and the workpiece. Specifically, the machining liquid supply nozzle is turned together with the wheel guard so that the wheel guard and the workpiece do not interfere with each other and, in response to reduced diameter of the grinding wheel due to wearing, the nozzle is adjusted with respect to the wheel guard by driving a motor, thereby to adjust the direction in which the machining liquid is supplied, or to move the wheel guard in a radial direction of the grinding wheel.
The fourth prior art, however, is a special machine tool, such as a surface grinder, and the wheel guard for covering the grinding wheel is an essential component. As a result, an attempt to mount a tool detachably on the spindle by an automatic tool changer such as in a machining center leads to the problem that the automatic tool changing operation cannot be achieved because the wheel guard interferes with the tool changing operation of the automatic tool changer. The disadvantage of this prior art, therefore, is the lack of versatility of applicability to the machining portions of various machine tools other than the surface grinder. Furthermore, the known grinding machine does not have any axis about which the workpiece is rotated, and can feed the workpiece only linearly along three axes, i.e., X-, Y- and Z-axes. Consequently, it has the problem that some workpieces of a particular shape interfere unavoidably with the wheel guard, or that the machining liquid cannot be properly supplied to the machining area if the interference between the workpiece and the wheel guard is avoided. Also, there is no specific disclosure of a structure or an arrangement for rotating or radially moving the wheel guard, or the machining liquid supply nozzle associated with it, in response to the driving force from the motor. Therefore, the utility of this prior art is insufficient in view of practical use.
In addition, the fourth prior art is not provided with any tool measuring means for measuring the diameter of the grinding wheel and nothing is disclosed with regard to techniques of automatically adjusting the radial position of the machining liquid supply nozzle relative to the grinding wheel on the basis of an acquired measurement of the tool diameter of the grinding wheel when the grinding wheel is abraded or the diameter thereof is changed by dressing or truing. Further, an attempt to adjust the circumferential position of the machining liquid supply nozzle about the grinding wheel encounters the problem that the positioning over the entire circumference of the grinding wheel is hampered by the wheel guard.
Accordingly, a principal object of the present a invention is to provide a machine tool system and its machining liquid supply device capable of positioning a machining liquid nozzle included in the machining liquid supply device at an optimal position relative to an engaging area where a tool engages with a workpiece from the viewpoint of chip removal and cooling in accordance with a change in the diameter of a tool detachably mounted on a spindle or a change in a machining point of various machine tools not limited to a specific type of machine tool, while at the same time supplying the machine liquid into the engaging area.
Another object of the present invention is to provide a machine tool system and its machining liquid supply device capable of positioning a machining liquid nozzle of the machining liquid supply device at the optimal machining liquid supply position relative to an area where a tool engages with a workpiece, by moving the machining liquid supply device to a desired machining liquid supply position by means of a rotary mechanism free of a dead angle about a spindle of the machine tool system, and further by positioning the machining liquid nozzle at the optimal machining liquid position in cooperation with a linear movement mechanism for linearly moving the machining liquid nozzle in a radial direction or a turning movement mechanism for turning the machining liquid nozzle.
Further object of the present invention is to provide a machine tool system and its machining liquid supply device capable of starting a machining process, in the case where a tool is reconditioned, after repositioning the machining liquid nozzle automatically following a before-and-after change in a diameter of the reconditioned tool.
Specifically, according to a first aspect of the present invention, there is provided a machine tool system for machining a workpiece by moving a tool mounted on a spindle and the workpiece mounted on a table included in the machine tool system relative to each other in three directions along an X-axis, a Y-axis and Z-axis, which comprises:
a spindle head for rotatably supporting the spindle;
a column for movably supporting the spindle head;
a tool mounting means for detachably mounting the tool on the spindle;
a machining liquid supply means including a machining liquid nozzle for spouting a machining liquid toward a machining area where the tool engages with the workpiece, and connected by piping to a machining liquid source;
a cylindrical supporting means disposed in an area surrounding the circumference of the spindle for movably supporting the machining liquid nozzle of the machining liquid supply means;
a radial moving means for positioning, in a radial direction of the tool, the machining liquid nozzle of the machining liquid supply means supported on the cylindrical supporting means, by linearly moving or turning the machining liquid nozzle with respect to the tool; and
a circumferential moving means for positioning the machining liquid nozzle of the machining liquid supply means over the entire circumference of the tool by rotating the cylindrical supporting means.
Preferably, the radial moving means comprises a rack located on the machining liquid nozzle of the machining liquid supply means, a pinion movable relative to the cylindrical supporting means and in mesh with the rack, a worm wheel movable relative to the cylindrical supporting means together with the pinion, a worm in mesh with the worm wheel, and a linear movement motor fixed on the column for driving to rotate the worm.
Preferably, the radial moving means comprises a pinion located on the machining liquid nozzle of the machining liquid supply means, a worm wheel having a pinion in mesh with the pinion and being movable relative to the cylindrical supporting means, a worm in mesh with the worm wheel, and a turning movement motor fixed on the column for driving to rotate the worm.
Preferably, the circumferential moving means comprises a worm wheel integrated with the cylindrical supporting means, a worm in mesh with the worm wheel, and a rotating movement motor fixed on the column for driving to rotate the worm.
Preferably, the system further comprises a rotary table having at least one rotational feed shaft and a work rotating means for rotationally feeding the workpiece mounted on the rotary table.
In addition, preferably, in the case where the tool mounted on the spindle is a grinding wheel, the machine tool system further comprises a tool measuring means located in a part of a structure of the machine tool system for measuring a diameter or a tip position of the grinding wheel mounted on the spindle.
Moreover, preferably, in the case where the tool mounted on the spindle is a grinding wheel, the machine tool system further comprises a tool reconditioning means located on the column for truing or dressing an outer peripheral portion of the grinding wheel mounted on the spindle.
According to a second aspect of the present invention, there is provided a machining liquid supply device of a machine tool system for supplying the machining liquid to a machining area where a tool mounted on a spindle engages with a workpiece mounted on a table included in the machine tool system, which comprises:
a machining liquid supply means including a machining liquid nozzle for spouting the machining liquid toward the machining area and connected by piping to a machining liquid source;
a cylindrical supporting means disposed in an area surrounding the circumference of the spindle for movably supporting the machining liquid nozzle of the machining liquid supply means;
a radial moving means for positioning, in a radial direction of the tool, the machining liquid nozzle of the machining liquid supply means supported on the cylindrical supporting means, by linearly moving or turning the machine liquid nozzle with respect to the tool; and
a circumferential moving means for positioning the machining liquid nozzle of the machining liquid supply means over the entire circumference of the tool by rotating the cylindrical supporting means.
Preferably, the radial moving means comprises a rack located on the machining liquid nozzle of the machining liquid supply means, a pinion movable relative to the cylindrical supporting means and in mesh with the rack, a worm wheel movable relative to the cylindrical supporting means together with the pinion, a worm in mesh with the worm wheel, and a linear movement motor fixed on the column for driving to rotate the worm.
Preferably, the radial moving means comprises a pinion located on the machining liquid nozzle of the machining liquid supply means, a worm wheel having a pinion in mesh with the pinion and being movable relative to the cylindrical supporting means, a worm in mesh with the worm wheel, and a turning movement motor fixed on a part of a structure of the machine tool system for driving to rotate the worm.
Preferably, the circumferential moving means comprises a worm wheel integrated with the cylindrical supporting means, a worm in mesh with the worm wheel, and a rotating movement motor fixed on a part of a structure of the machine tool system for driving to rotate the worm.
By provision of the cylindrical supporting means for movably supporting the machining liquid nozzle of the machining liquid supply means for spouting the machining liquid toward the machining area where the tool engages with the workpiece, on the area surrounding the circumference of the spindle supported rotatably on the spindle head, the present invention can achieve operations of linearly moving or turning the machining liquid nozzle of the machining liquid supply means in the radial direction of the tool by means of the radial moving means located on the cylindrical supporting means, and rotating the machining liquid nozzle of the machining liquid supply means over the entire circumference about the tool, thereby positioning the machining liquid nozzle so as to spout the machining liquid toward the machining area.
The machine tool system and the machining liquid supply device according to the invention having the arrangement and operations as described above, in performing the machining process such as grinding or cutting on the workpiece W by a machining tool T such as a grinding wheel or a milling cutter of the machine tool MT, can supply and spout the machine liquid through the machining liquid supply nozzle of the machining liquid supply device to the machining area or the contact area P of the tool T from the optimum machining liquid supply position, i.e. from the most proper position for removing the machining chips and cooling both the tool T and the workpiece W. Further, when setting the opening end of the machining liquid supply nozzle in most proper position and orientation for optimal machining liquid supply, the machining liquid supply device itself can be rotated over the entire circumference about the rotational axis of the spindle. Therefore, the setting of the position and orientation can be performed without any difficulty in spite of the change in any of the various conditions such as the shape and the limitation of the installation of the workpiece W.
It should be understood from the foregoing description that the present invention is not limited to the grinding machine for performing the grinding process but is applicable as it is to the other machine tool system such as a cutting machine using a milling cutter with equal effect.
In addition, according to the present invention, even if the diameter of the tool in use is changed by the exchange of the tools T such as the grinding wheel T using the tool changing means or the wear of the tool in use causes the change in the diameter thereof, the tool diameter can be measured and the setting of the position and orientation of the machining liquid supply nozzle of the machining liquid supply device can be properly adjusted and moved on basis of the measured tool diameter. In this way, the machining liquid can be always supplied from the optimal position to the machining area of the tool.
As described above, in view of the fact that the position for supplying the machining liquid to the machining area of the tool of the machine tool system can be always set in an optimal condition for cooling function and chip removal function, both the machining accuracy and the surface roughness can be remarkably improved in the machining operation applied by the tool T to the workpiece W. Further, the machining tool can be always properly and effectively cooled while at the same time removing the chips. This can decrease the wearing of the tool and results in a reduced machining cost.
Also, this invention is so configured that the setting and the positioning of the machining liquid supply nozzle of the machining liquid supply device can be automatically achieved in both radial and circumferential directions with respect to the axis of the spindle, respectively, by the rotating movement means and linear movement or turning movement means including a driving motor with a servo motor as a driving source. The application of the invention to the automatic machine tool such as a machining center, therefore, can contribute to the optimization of the automatic supply of the machining liquid.
Comparison of the present invention with the above-mentioned four prior art will be described below. The first prior art is so configured that the position of the machining liquid nozzle can be adjusted only in a direction along the diameter, i.e. radially of the tool (grinding wheel). The second and third prior art are so configured that the position of the machining liquid supply nozzle can be adjusted only in a circumferential direction, i.e. in a direction tangential to the tool (grinding wheel) at the machining point. According to the present invention, in contrast, the position of the machining liquid nozzle can be adjusted in both radial and circumferential directions of the tool, and therefore the machining liquid can be supplied from the optimal position in response to the change in the tool diameter or the machining point. Further, the fourth prior art is so configured that the position of the machining liquid nozzle can be adjusted in both the radial and circumferential directions of the tool, but the adjustment of the circumferential position is limited. In contrast, the present invention is free of such a limitation of the position of adjusting the machining liquid nozzle in the circumferential direction of the tool, and configured so that the position adjustment is possible over the entire circumference of the tool. Therefore, the machining liquid can be supplied properly without any dead angle.